The History of Clocks:
What comes to mind when we hear or read the word, clock? Alarm clocks, clock towers, wall clocks, cuckoo clocks, grandfather clocks, and the list goes on. And yet, these images relate to only one specific type of timepiece: the mechanical clock, which was invented in Asia around 800 AD. Clock comes from the Latin word meaning bell; implying the name was given after the invention of the mechanical device which contained a striking instrument. At set intervals, a bell, chime, or gong is struck, producing the bell sound, and thus giving it the name, clock. A clock without a ringing sound is actually called a timepiece.
A clock, in the broadest sense of the word, is any instrument that measures any change over any passage of time, whether minute, hour, day, month, season, lunar cycle, stellar cycles, etc. In this respect, a calendar falls under the heading of a timepiece. Clocks, or time-measuring devices, are mankind's oldest invention. With this in mind, we can have a much clearer view of clock history and a greater appreciation for the intelligence of ancient mankind.
Various instruments used for measuring the passage of time pre-dates history, followed thousands of years later by early clocks and timepieces; later, by mechanical clocks; and then, most recently, with the digital and atomic clocks. As early as 30,000 years ago, prehistoric man studied and accurately recorded lunar cycles by carving notches in pieces of wood or bone. In this way, prehistoric man was already developing his clock and learning to measure the passage of time in his world. By 8,000 years ago, man understood the solar phases in relation to the earth, which not only correlated with the seasons but also to the passage of time during day and night. Sun sticks, a primitive time-measuring device, were used primarily to note high noon and the solstices; simultaneously, comprehensive calendars had been developed showing weeks, months, and years, as well as the eighteen-year lunar cycle. By 3,500 years ago, water clocks were well developed in Asia, and sophisticated sundials were being used in Egypt. Both of these time-measuring devices are considered to be the earliest forms of what we recognize as clocks, as they kept near-accurate time throughout the day. Of course, sundials weren't effective during nighttime or on overcast days. However, water clocks were much more precise and predictable since they did not rely upon sunlight.
The earliest mechanical clock, invented around 800 AD in China, was said to contain a small [mechanical] bird that announced the hours. Various forms of mechanical timepieces and water clocks were developed over the following years throughout the Mediterranean countries of Italy, Greece, Egypt, and Arabia. Though few of these original timepieces and clocks still exist today, there are many written records and drawings of such clocks, as inventions, gifts, and built within temples and monuments.
By the Middle Ages in Europe, all known time devices were being used strictly within the churches. Prayer, worship, and various other duties were to be held at specific times of the day and it therefore fell to the monks to be the time keepers and custodians of the clocks. There are no surviving clocks prior to the 13th century in Europe, but many church records detail the tower clocks and other incorporated time-measuring devices used by the church. Monks never gave up their secrets, not even in church documents, and therefore, much of this portion of clock history is speculation and pieced together with what facts we do know of the time.
By the 14th century, the invention of all four key elements found in every clock used thereafter and up to the present day, excluding digital clocks, had been developed. These elements have been improved upon and added to in each subsequent century. The pendulum clock and long clock, or grandfather clock, was invented in the 17th century, and the first electric clock was patented the following century, in 1840. Electronic advancements in the 20th century led to clocks with no actual clock-working parts at all. Rather, our modern clocks rely on such functions as the vibration of a tuning fork, quartz crystals, radioactive elements, or the resonance of polycarbonates. What we know as mechanical clocks are almost entirely battery powered, which removes the need for winding.